airplay icon disappears on ipod touch 4g - all other devices work

HELP!!! I bought apple tv yesterday and it works on my new macbook air, my macbook pro, my iPad 2, iphone 4s and iphone 5. However, my daughter's 4G iPod touch gets the airlplay icon but as soon as we try to play something she either gets an error on the tv that there was a problem with the content and the airplay icon disappears. She is unable to use apple tv and the same content works from every other device! we are all on the same wifi and network.